In the past, little attention was paid to the storage or recycling of refrigerant. When refrigeration systems were being repaired or when the refrigerant, such as those sold under the brand name FREON, was contaminated sufficiently to affect the effectiveness of refrigeration, the refrigerant was vented into the atmosphere.
Recent developments have, however, created a demand for systems capable of storing refrigerant while at the same time purifying the contaminated refrigerant. The United States, as have several other countries, has become a signatory of the "Montreal Protocol on Substances that Deplete the Ozone Layer," which restricts future production of fully halogenated chlorofluorocarbons. Pursuant to this international mandate, future production of all currently used refrigerants are to be drastically cut by the end of the century. In addition to this development, the United States Environmental Protection Agency has classified several widely used refrigerants as hazardous substances under the Resource Conservation and Recovery Act ("RCRA").
The combination of these two regulatory developments accentuates the necessity for a device which will store and purify refrigerant, eliminating the possibility of unlawful emissions and the necessity for purchasing refrigerants in an artificially constrained market. The present invention relates to improvements on the refrigerant reclaim apparatus as described in U.S. Pat. No. 5,195,333 of Van Steenburgh, Jr.
The co-pending application discloses an apparatus for drawing refrigerant from a container, or a refrigeration system to be repaired, heating the refrigerant sufficiently to maintain it in a gaseous state while it passes through an oil separator into the intake of a compressor. Compressed gaseous refrigerant is discharged from the compressor and passed through a heat exchanger to heat the incoming liquid refrigerant and then passes through to a condenser where it is liquefied. The liquefied refrigerant is passed from the condenser into a storage tank from the bottom of which liquid refrigerant flows through a filter-drier and an expansion device for reconverting the liquid refrigerant to a gaseous form. From the expansion device the gaseous refrigerant passes through a coil submerged in the liquid in the storage tank and then is passed back to the intake of the compressor.
The temperature of the liquid in the storage tank is lowered by the chilling effect of the expanding gaseous refrigerant passing through the coil submerged in the liquid. The refrigerant can be repeatedly passed from the chill tank through the filter-drier, expansion device, cooling coil, compressor, heat exchanger, condenser and back to the storage tank. This repeated process will progressively lower the temperature of refrigerant in the storage tank.
The apparatus described in the co-pending application provides several advantages over the prior art. There are, however, several additional attributes that are desirable in refrigerant reclaim systems. In particular, when purging air from the system, it has become increasingly desirable to reduce the amount of vaporized refrigerant that is entrained with the air that is being purged.
When air is present in a refrigeration reclaim system, it becomes trapped on the high pressure side of the system in the space above the liquid refrigerant in the storage tank. Here it becomes an homogeneous mixture with the refrigerant vapor and adds its partial pressure to the refrigerant saturation pressure. This increased pressure causes the system to function less efficiently because the compressor must pump against this additional high side pressure. It is, therefore, desirable to eliminate air (or, more generally, all noncondensable gases) from refrigerants in a refrigerant handling system such as a refrigerant reclaim.
While an air vent such as that shown in co-pending application Ser. No. 07/332,235 now U.S. Pat. No. 5,195,333 of Van Steenburgh, Jr. will remove air from the storage tank, it also releases a quantity of vaporized refrigerant into the atmosphere. This is costly both from an economic and from an environmental perspective. What is desired is an automatic air purge apparatus that will remove air and other noncondensable gases from the refrigerant being handled.
Air purge systems for removing air from a refrigerant reclaim or other refrigerant handling system are described in U.S. Pat. Nos. 5,005,369 of Manz and 5,063,749 of Manz. The air purge system of this invention takes the different approach to the problem which is exemplified in U.S. Pat. No. 5,291,743, and discloses certain improvements related thereto.